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TutorialsERC-20 Transfers

ERC-20 Transfers

Send and receive ERC-20 tokens with your smart wallet.

This tutorial covers transferring ERC-20 tokens using both the Core SDK (backend) and the UI Kit (frontend). You will use the encodeERC20Transfer helper for backend transfers and the useSendTransaction hook with assetType: 'erc20' for frontend transfers.

Prerequisites

  • Node.js 18+ installed
  • An EmbarkAI API key from the Dashboard 
  • A deployed wallet with ERC-20 tokens (see Deploy a Smart Wallet)
  • The token contract address and decimals for the ERC-20 you want to transfer

Backend Approach

Step 1: Encode the Transfer

Use encodeERC20Transfer to generate the calldata for a standard transfer(address,uint256) call:

import {
  createServerWalletManager,
  MemoryKeyshareStorage,
  encodeERC20Transfer,
} from '@embarkai/core'
 
const tokenAddress = '0xTokenContractAddress'
const recipientAddress = '0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb'
const amount = '1000000' // 1 USDC (6 decimals)
 
const calldata = encodeERC20Transfer(recipientAddress, amount)

Step 2: Send the UserOperation

Pass the encoded calldata to sendUserOperation with the token contract as the to address and 0 as the value (ERC-20 transfers do not send native tokens):

const manager = createServerWalletManager({
  apiKey: process.env.EMBARK_API_KEY!,
  chainId: 994873017,
  storage: new MemoryKeyshareStorage(),
})
 
const wallet = await manager.getWallet('my-wallet')
 
const userOpHash = await wallet.sendUserOperation(
  tokenAddress,  // to: the token contract
  '0',           // value: 0 (no native transfer)
  calldata,      // data: encoded transfer call
)
 
const receipt = await wallet.waitForUserOperationReceipt(userOpHash)
console.log('Transfer TX:', receipt.transactionHash)

Frontend Approach

Step 1: Set Up the Provider

import { Provider, ConnectWalletButton } from '@embarkai/ui-kit'
 
function App() {
  return (
    <Provider
      projectId={process.env.NEXT_PUBLIC_PROJECT_ID!}
      chainId={994873017}
    >
      <ConnectWalletButton />
      <TokenTransfer />
    </Provider>
  )
}

Step 2: Send an ERC-20 Transfer

Use useSendTransaction with assetType: 'erc20'. The hook handles encoding internally:

import { useSendTransaction } from '@embarkai/ui-kit'
 
function TokenTransfer() {
  const { sendTransaction, isLoading, userOpHash, error } = useSendTransaction()
 
  const handleTransfer = async () => {
    await sendTransaction({
      to: '0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb',
      value: '1000000',          // Amount in token's smallest unit
      assetType: 'erc20',
      tokenAddress: '0xTokenContractAddress',
      decimals: 6,               // Token decimals (e.g., 6 for USDC)
    })
  }
 
  return (
    <div>
      <button onClick={handleTransfer} disabled={isLoading}>
        {isLoading ? 'Transferring...' : 'Send 1 USDC'}
      </button>
      {userOpHash && <p>UserOp: {userOpHash}</p>}
      {error && <p>Error: {error.message}</p>}
    </div>
  )
}

SendTransactionParams for ERC-20

ParameterTypeDescription
tostringRecipient address
valuestringAmount in the token’s smallest unit (wei equivalent)
assetType'erc20'Indicates an ERC-20 transfer
tokenAddressstringThe ERC-20 contract address
decimalsnumberToken decimal places (e.g., 18 for most tokens, 6 for USDC)

Approve + TransferFrom Pattern

Some use cases require the two-step approve/transferFrom flow — for example, when interacting with a DEX or staking contract.

Step 1: Approve the Spender

Use encodeContractCall to encode an approve call:

import { encodeContractCall } from '@embarkai/core'
 
const approveCalldata = encodeContractCall({
  abi: ['function approve(address spender, uint256 amount) returns (bool)'],
  functionName: 'approve',
  args: ['0xSpenderContractAddress', BigInt('1000000')],
})
 
const approveHash = await wallet.sendUserOperation(
  tokenAddress,
  '0',
  approveCalldata,
)
 
await wallet.waitForUserOperationReceipt(approveHash)
console.log('Approval confirmed')

Step 2: Execute TransferFrom

The spender contract can now call transferFrom on behalf of your wallet. If you need to trigger this from your own wallet (e.g., in a batch), encode it similarly:

const transferFromCalldata = encodeContractCall({
  abi: ['function transferFrom(address from, address to, uint256 amount) returns (bool)'],
  functionName: 'transferFrom',
  args: [wallet.smartAccountAddress, '0xRecipientAddress', BigInt('1000000')],
})
 
const txHash = await wallet.sendUserOperation(
  tokenAddress,
  '0',
  transferFromCalldata,
)

Complete Backend Code

import {
  createServerWalletManager,
  MemoryKeyshareStorage,
  encodeERC20Transfer,
} from '@embarkai/core'
 
async function main() {
  const manager = createServerWalletManager({
    apiKey: process.env.EMBARK_API_KEY!,
    chainId: 994873017,
    storage: new MemoryKeyshareStorage(),
  })
 
  const wallet = await manager.getWallet('my-wallet')
  const tokenAddress = '0xTokenContractAddress'
 
  // Encode and send an ERC-20 transfer
  const calldata = encodeERC20Transfer(
    '0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb',
    '1000000', // 1 USDC
  )
 
  const userOpHash = await wallet.sendUserOperation(
    tokenAddress,
    '0',
    calldata,
  )
 
  const receipt = await wallet.waitForUserOperationReceipt(userOpHash)
 
  if (receipt.success) {
    console.log('ERC-20 transfer confirmed:', receipt.transactionHash)
  }
}
 
main().catch(console.error)

Next Steps

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